Sunday, October 30, 2011

Autumnal Larvae

In the space of seven days most wild larvae have coloured up, with only two out of nine still looking green. This is unusually rapid progress. They have now suddenly caught up with their domesticated cousins.

Autumn larvae spend much time hiding in the rain drop that gathers on the downward-facing leaf tip. Today one suddenly crawled out from his rain drop, in steady drizzle, preceded to add a bit more silk to strengthen his seat leaf on to the twig, before returning back to his drip! Temperature at the time was 13C. I don't care what mistakes people make in life only please don't underestimate a caterpillar. Below are two wild larvae having a great time in rain drops.

My data suggests that autumn larval survival (on the leaf) may actually be higher in wet autumns and lower in dry autumns such as 2011.... This needs proper and careful analysis, not least because other factors may well be at play - notably annual tit breeding success and resultant predator population size. Whatever, late summer - autumn survival on leaves has been lower this year.... which doesn't auger well for 2012 adult numbers.

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